Original Research

Expression of Glial Fibrillary Acidic Protein (GFAP) in the Trigeminal of Male Wistar Rats

P.K. Sankaran1,*, M.Kumaresan2, G. Karthikeyan3, Yuvaraj M.4

1,3Assistant Professor, 2,4Tutor, Dept. of Anatomy, Saveetha Medical College & Research Institute, Chennai

*Corresponding Author: Email: [email protected]

ABSTRACT Background Significance: The pseudounipolar in the sensory ganglia are wrapped by small satellite cells which play a similar role like Schwann cells in the peripheral . The pseudounipolar cells of are surrounded by a capsule formed by satellite glial cells. These satellite glial cells play important role in maintaining normal functions of the . Aim & Objective: To localise GFAP in satellite glial cells of trigeminal ganglion. Material & Methods: Six male wistar albino rats trigeminal ganglion were collected and immunohistochemically stained for GFAP in six male wistar albino rats. Result: GFAP was localised in the of satellite glial cells surrounding the neurons. GFAP was also localised around Schwaan cells of an . Discussion: GFAP is an intermediate protein which can get up regulated due to peripheral axonal injury. This GFAP can trigger mediators of inflammation and create a neuralgia or like conditions. Conclusion: This study concluded that satellite cells are type of glial cells that express GFAP. This GFAP was also expressed by Schwaan cells surrounding the axon.

Keywords: GFAP, Trigeminal ganglion, Satellite glial cells, Pseudounipolar neurons

Access this article online stages of inflammation and pain associated with Quick Response several CNS diseases.4 Glial cells express Code: Website: characteristic substances in common with immune www.innovativepublication.com cells in which they respond to viruses and bacteria, releasing pro-inflammatory , which create DOI: pathological pain.4 GFAP is a member of the 10.5958/2394-2126.2015.00008.0 cytoskeletal protein family, and the principal 8-9 nm

intermediate filaments expressed in mature of the , and satellite glial cells INTRODUCTION (SGC) of sensory ganglia.5 The trigeminal ganglion (also called the semilunar ganglion or Gasserian ganglion) is mainly AIM AND OBJECTIVE composed of cell bodies of pseudounipolar neurons To study, the expression of GFAP in the and nerve fibres. The cell bodies, predominantly trigeminal ganglion of male wistar albino rats. occupy the peripheral part of the ganglion, while the nerve fibres occupy mainly the central regions. The MATERIALS AND METHOD trigeminal ganglion contains the first order neurons Male albino Wistar rats (n=6) of weight of the somatosensory pathways arising from receptors ranging from 200g to 250g was used for and free nerve endings in the facial and oral tissues, Immunohistochemical localization of GFAP in scalp and part of the duramater.1 There is various trigeminal ganglia of each side. The rats were neurological disorders like migraine and neuralgia obtained from experimental animal facility of All which are associated with the trigeminal ganglion. India Institute of Medical Science after prior approval Migraine is a major disorder resulting due to the of the experimental procedure by Institutional Animal consequences of multiple pathophysiological changes Ethics Committee (IEAC). The animals were kept in in the meningeal tissues, trigeminal ganglion, cages with not more than three animals in one cage. trigeminal stem nuclei based on specific They were maintained at 12hr: 12hr light/dark cycles characteristic of trigeminal vascular system.2 with water and food available ad libitum Glial cells which surround the pseudo unipolar neurons directly modulate neuronal function TISSUE COLLECTION AND and activity by changing the ionic concentrations in IMMUNOHISTOCHEMICAL LOCALIZATION and around the neurons.3 Interestingly, neuron- Fixation was done by using 500ml of 4% interactions have been shown to be involved in all paraformaldehyde in 0.1 M phosphate buffered Indian Journal of Clinical Anatomy and Physiology 2015;2(3):145-147 145 Sankaran et al. Expression of Glial Fibrillary Acidic Protein (GFAP) in the Trigeminal Ganglion… saline, through continuous transcardiac perfusion for extracellular space between the neuron and satellite a period of 1 hour. Then the skull was cut open and glial cell is minimal.5 trigeminal ganglion was identified and removed. GFAP is important in modulating Then the ganglia were placed in chuck embedded motility by providing structural stability to astrocytic with Optimum Cutting Temperature medium and processes.7 Glial fibrillary acidic protein (GFAP) the sectioned using cryostat (20Hm). For each tissue the archetypal marker for astrocytes is reported to be sections were collected separately in the multi vial present at either low level in the normal satellite glial culture plates and labelled. For free floating cells or in activated satellite glial cells.8 Following immunohistochemical localization the antibodies for peripheral nerve injury, satellite glial cells undergo GFAP was obtained from Sigma Laboratories (USA). changes similar to those found in CNS and show The dilutions ratio for GFAP (1:400) was determined marked increase in glial fibrillary acidic protein after repeating the histochemical localization at (GFAP).9 There is increasing evidence that glia various dilution ratios. The slides stained for GFAP within the spinal cord dorsa horn contributes to the were captured by ProgRes image capture using maintenance of pathological pain.4 In chronic JENOPTIK ProgRes Capture Pro 2.7 (Germany) in constriction injury of the sciatic nerve there was up- an E-600 Nikon compound light microscope. regulation of TNF-alpha leading to over expression of GFAP in the neurons. Also, it RESULT was noted that this TNF-alpha signalling pathway is Immunolocalisation for GFAP: the major pathological change leading to a) GFAP was localised in the cytoplasm of satellite inflammatory pain.10 glial cells (black arrow). Increased GFAP immunostaining was b) GFAP was also localised in schwaan cells (blue observed in the gray matter of the spinal cord arrow). ipsilateral to the lesion and specific to spinal segments in which the sciatic nerve is distributed. Elevated GFAP staining density was attributed primarily to hypertrophy of astrocytes rather than their proliferation or migration since counts of astrocyte profiles demonstrated no significant difference when comparing the lesion to the control side. The magnitude of the increase in GFAP staining correlated with the degree of .11 In the present study glial fibrillary acidic protein (GFAP) was localized around the i.e. Schwann cells. This finding is supported by a study where they showed that the peripheral nerve regeneration is disturbed in mice that lack glial fibrillary acidic protein (GFAP), a Schwann-cell- specific cytoskeletal constituent which was up regulated after damage.12

CONCLUSION This study concludes that GFAP is expressed by glial cells of trigeminal ganglion

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